大渡河流域水系连通性与水电梯级开发的耦合分析研究

Coupling Analysis of River-System Connectivity and Cascade-Hydropower Development inthe Dadu River Basin

为探究山地流域水电梯级开发对水系连通性的影响,厘清二者交互耦合规律,以大渡河流域为靶区,采用复杂网络方法模拟现实情景,构建水系连通指数指标(HC)和水电开发产量指标(E)和协调发展度(D)分析流域水电梯级开发引起的水系结构特征变化及造成的生态过程影响.得出了以下结论:(1)水电站修建的数量及位置对于流域水系连通性产生不同程度的影响.水电站修建数量的增加,流域水系连通程度呈逐渐降低的趋势,但水系连通指数降速减缓,呈快速下降-稳定下降-波动下降三个阶段;水电站位于中游比位于上游或下游产生的影响更大;水电站分散建设较之集中建设,加剧了流域水系网络的破碎化程度,且此时修建位置的影响力大过修建数量.(2)山地流域水系连通性与水电梯级开发的耦合曲线呈倒"U"型,拐点与水系连通指数、水电开发产量变化曲线的交汇点保持一致,并得到大渡河流域水电梯级开发的经验公式,由此构建山地流域水电梯级开发与水系连通性的耦合模型,并在大渡河流域实证研究中对其耦合规律划分为生态衰退—耦合发展—生态失调—人工干预阶段四个阶段.研究结果可为山地流域梯级水电开发提供科学参考,也可为区域范围内相关水资源开发的同类研究提供方法借鉴.

To explore the impact of cascade-hydropower development in mountain basins on river-system connectivity(and to reveal their coupling law),the current study selected the Dadu River Basin as a study area and simulated real-life scenarios using the complex network method.Additionally,related indexes including hydrographic net connectivity(HC),hydropower development output(E),and the coordinated development degree(D)were constructed to analyze changes in water-system structure characteristics caused by cascade-hydropower development in the basin and its influences on ecological processes.The results of the study are as follows.First,the number and location of cascade-hydropower stations were found to differentially influence river-system ecological processes.Furthermore,it was found that,with an increase in the number of cascade-hydropower stations,river-system connectivity in the basin tended to gradually decrease.However,the reduction of the HC index was found to slow down in three main stages:the rapid-reduction stage,stable-reduction stage,and fluctuating-reduction stage.Additionally,hydropower stations in the middle reaches were found to have a greater impact compared with those upstream or downstream.Compared with centralized construction,the decentralized construction of hydropower stations intensified the fragmentation of the river network,and the influence of construction location was greater than the number of constructions.Second,the coupling curve between water-system connectivity in maintaining basins and cascade-hydropower development was found to be an inverted"U"type,and its inflection point was consistent with the intersection of the coupling curve between the HC and E indexes.Furthermore,the empirical formula for cascade-hydropower development in the Dadu River Basin was obtained,and based on this,a coupling model between cascade-hydropower development and water-system connectivity in maintaining basins was constructed.The associated coupling law was divided into four stages in this study specifically,development in ecological-recession coupling,ecological imbalance,and manual intervention.The findings of the current study provide a reference point for cascade-hydropower development in mountain basins and offer guidance for similar studies on relevant regional water-resource development.